Showing papers on "Pincer movement published in 2006"
TL;DR: An air and moisture-stable nickel(II) complex of bis-carbene pincer complex 2 has been synthesized, and its catalytic activity for the Heck reaction and the Suzuki coupling reaction was investigated as mentioned in this paper.
140 citations
TL;DR: In this paper, a bis(phosphine) pincer complex of iridium based on ferrocene and ruthenocene has been synthesized, and the reaction of 1,3-bis((di-tert-butylphosphino)methyl)metallocenes [t-BuP,CH,PM] (M = Fe, 10; M = Ru, 13) with [Ir(COE)2Cl]2 in refluxing toluene leads to the corresponding chloro-hydrido pincers as a
122 citations
TL;DR: In this paper, the synthesis of bisimino nickel(II) NNN pincer complexes of the type [NiCl 2 {C 5 H 3 N-2,6-(CHNAr f ) 2 }] has been achieved and their reactivity in alkyl and arylthiolation reactions of halobenzenes examined.
Abstract: The synthesis of bis-imino nickel(II) NNN pincer complexes of the type [NiCl 2 {C 5 H 3 N-2,6-(CHNAr f ) 2 }]; Ar f =C 6 H 3 -2,3-F 2 (1), C 6 H 3 -2,5-F 2 (2), C 6 H 3 -3,4-F 2 (3), C 6 H 3 -3,5-F 2 (4), C 6 H 2 -2,3,4-F 3 (5), C 6 H 2 -2,3,6-F 3 (6), C 6 H 2 -2,4,5-F 3 (7), C 6 H 2 -2,4,6-F 3 (8), has been achieved and their reactivity in alkyl- and arylthiolation reactions of halobenzenes examined. The use of fluorinated substituents Ar f on the imines has allowed the tuning of the electronics in these complexes and the influence of these substituents and those of the disulfides in the thiolation reactions have been analyzed.
109 citations
TL;DR: In this paper, a combination of X-ray crystallography, NMR spectroscopy, and DFT computational techniques were used to characterize the products and determine the mechanisms of the C−H cleavage.
Abstract: Bulky pincer complexes of ruthenium are capable of C−H activation and H-elimination from the pincer ligand backbone to produce mixtures of olefin and carbene products. To characterize the products and determine the mechanisms of the C−H cleavage, reactions of [RuCl2(p-cymene)]2 with N,N‘-bis(di-tert-butylphosphino)-1,3-diaminopropane (L1) and 1,3-bis(di-tert-butylphosphinomethyl)cyclohexane (L2) were studied using a combination of X-ray crystallography, NMR spectroscopy, and DFT computational techniques. The reaction of L1 afforded a mixture of an alkylidene, a Fischer carbene, and two olefin isomers of the 16-e monohydride RuHCl[tBu2PNHC3H4NHPBut2] (2), whereas the reaction of L2 gave two olefin and two alkylidene isomers of 16-e RuHCl[2,6-(CH2PBut2)2C6H8] (3), all resulting from dehydrogenations of the ligand backbone of L1 and L2. The key intermediates implicated in the C−H activation reactions were identified as 14-electron paramagnetic species RuCl(PCP), where PCP = cyclometalated L1 or L2. Thus the ...
86 citations
TL;DR: The synthesis of a range of chiral palladium bis(phosphite) pincer complexes has been achieved via C-H activation of the parent ligands and one of the complexes formed shows good activity in the catalytic allylation of aldehydes.
86 citations
TL;DR: In this paper, the Ag(I) complex of bis[2-(3-methylimidazolin-2-yliden-1-yl)ethyl] ether (MeCOC) was prepared through the reaction of the corresponding bis-imidazolium salt with Ag2O and crystallographically characterized as the triflate salt.
86 citations
TL;DR: In this article, the PCsp3P pincer complexes are characterized by NMR spectroscopy and, in the case of 1, 4, and 5, by X-ray crystallography.
83 citations
TL;DR: In this paper, two types of luminescent pincer platinum complexes with κ3S,C,S and κ 3N, C,N coordination modes were obtained, and the decay lifetimes were in the range 10-5−10-6 s.
66 citations
TL;DR: The precursors of the fragment (PCP)Ir have been previously reported to react with dinitrogen to give the bridging dinuclear complex [(PCP]Ir]2(N2) (2), which was crystallographically characterized in this paper.
56 citations
TL;DR: The first chiral bis(pyridine) N-C-H-N pincer ligand was synthesized and characterized by a thorough 1 H NMR analysis as mentioned in this paper.
56 citations
TL;DR: NMR spectroscopic study indicated that a sigma-allylpalladium intermediate was formed and possibly functions as the nucleophilic species that undergoes addition to the aldehydes.
Abstract: An air- and moisture-stable SeCSe−Pd(II) pincer complex was synthesized and found to catalyze the nucleophilic allylation of aldehydes with allyltributyltin. The allylation of a variety of aromatic...
TL;DR: The syntheses and molecular structures of the bromo-substituted triarylphosphane sulfide (3-Br-5-t-Bu-C6H3)P(S)Ph2 (1) were given in this article.
TL;DR: In this article, two new p -alkoxycarbonylated palladium bis(phosphinite) PCP pincer complexes are easily prepared and for the first time evaluated as homogeneous catalysts in α-arylation of ketone enolates.
TL;DR: Palladium pincer complexes composed of six-membered fused metallacycles have been synthesized directly from 1,3-bis(2-pyridyloxy)benzene as discussed by the authors.
TL;DR: A variety of PCP pincer palladium complexes having phosphinito groups [2,6-(R2PO)2C6H3PdI (R = alkyl, aryl and Et2N)] were synthesized via the electrophilic ligand introduction route with high efficiency as mentioned in this paper.
TL;DR: Poly(norbornene)-based block copolymers containing side chains of palladated pincer complexes/dibenzo[24]crown-8 or palladator complexes/ dibenzylammonium salts were synthesized and it was found that theSelf-assembly of the recognition units along each polymer block does not preclude the self-assembly processes along the other block.
Abstract: Poly(norbornene)-based block copolymers containing side chains of palladated pincer complexes/dibenzo[24]crown-8 or palladated pincer complexes/dibenzylammonium salts were synthesized. Noncovalent functionalization was accomplished with their corresponding recognition units through simple 1:1 addition with association constants (Ka) greater than 10(5) m(-1). The self-assembly processes were monitored by using both 1H NMR spectroscopy and isothermal titration calorimetry. In all cases, we found that the self-assembly of the recognition units along each polymer block does not preclude the self-assembly processes along the other block.
TL;DR: Chiral C2-symmetric bis(imidazoline) pincer ligands 2a-d have been synthesized for the first time by direct cycloplatination of these ligands with K2PtCl4 in dry acetic acid as discussed by the authors.
TL;DR: The pincer-type carbene complexes Rh(C-N-C)Cl and Rh(N-N)-NCl have been characterised by spectroscopic and diffraction methods as discussed by the authors.
Abstract: The “pincer”-type carbene complexes Rh(C–N–C)Cl and
Rh(C–N–N)Cl [C–N–C = 3,3!-diaryl-1,1!-pyridine-2,6-diylbis-
(imidazol-2-ylidene), C–N–N = 1-aryl-3-(2,2!-bipyridin-6-yl)-
imidazol-2-ylidene] have been prepared and characterised
by spectroscopic and diffraction methods. They bind CO to
give cationic complexes but are inert to H2. Both oxidatively add CH2Cl2 to give octahedral RhIII complexes. Theoretical
calculations provide insight into the bonding of the Rh(C–N–
C)Cl and Rh(C–N–N)Cl complexes.
TL;DR: A chiral NCN ligand, (5 R, 7 R )-1,3-bis(6,6-dimethyl-5,6,7,8-tetrahydro-5-7-methanoquinolin-2-yl)benzene has been synthesized as discussed by the authors.
TL;DR: In this paper, the shortest OO bond was reported for RhO2 complexes, indicating the formation of a RhIO2 adduct, rather than a cyclic RhIIIη2-peroxo complex.
Abstract: Treatment of [{Me2C6H(CH2PtBu2)2}Rh(η1-N2)] (1a) with molecular oxygen (O2) resulted in almost quantitative formation of the dioxygen adduct [{Me2C6H(CH2PtBu2)2}Rh(η2-O2)] (2a). An X-ray diffraction study of 2a revealed the shortest OO bond reported for RhO2 complexes, indicating the formation of a RhIO2 adduct, rather than a cyclic RhIIIη2-peroxo complex. The coordination of the O2 ligand in 2a was shown to be reversible. Treatment of 2a with CO gas yielded almost quantitatively the corresponding carbonyl complex [{Me2C6H(CH2PtBu2)2}Rh(CO)] (3a). Surprisingly, treatment of the structurally very similar pincer complex [{C6H3(CH2PiPr2)2)}Rh(η1-N2)] (1b) with O2 led to partial decomposition, with no dioxygen adduct being observed.
TL;DR: In this paper, the reaction of cis-and trans-1,3-bis(di-t-butylphosphinomethyl)cyclohexane (cis- and trans-PCyP), with rhodium and palladium chlorides afforded Cs and C1 symmetrical pincer complexes, where the PCyP ligands are coordinated in a meridianal fashion through the two phosphorus atoms and the cyclometalated C-1 carbon of the cyclohexANE ring.
TL;DR: In this paper, a new class of palladium pincer complexes bearing m-terphenyl scaffolds have been synthesized and structurally characterized, as a result of integrating phenyl rings into the chelating arms of m-xylyl type pincers.
TL;DR: In this paper, the crystal structures of resorcinol 2-methyl-4,6-di-tert-butyl (2-methyl)-4, 6-di-, 4, 6,di-TERT, and mono-diisopropylphosphinite derivative were determined.
TL;DR: In this paper, the PNP pincer ligands featuring phosphoramidites in CH2Cl2 were treated with NiBr2(DME) or anhydrous NiBr 2 with 2 equiv.
Abstract: Treatment of NiBr2(DME) (DME = 1,2-dimethoxyethane) or anhydrous NiBr2 with 2 equiv. of PNP pincer ligands featuring phosphoramidites in CH2Cl2 yields the novel neutral pentacoordinate complexes [Ni(PNP){κ1(P)-R2P=O}Br]. Over the course of this reaction the P–N bonds of the phosphoramidite units of one PNP ligand are selectively cleaved due to hydrolysis affording an anionic κ1-(P)-coordinated phosphinite ligand [R2P=O]–, while a second PNP ligand remains intact and is coordinated in a κ3-(P,N,P) fashion. The X-ray structure of one [Ni(PNP){κ1(P)-PR2=O}Br] complex has been determined.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
TL;DR: In this article, a simple and effective two-step synthesis of ferrocene pincer ligands is described starting from readily available N,N -dimethylaminomethylferrocene.
TL;DR: In this article, a neutral NCN-pincer palladium bromide complex with bis-ortho-(S)-prolinol substituents was synthesized and isolated as a mixture of three stereoisomers.
Abstract: Neutral NCN-pincer palladium bromide complex 2 containing the monoanionic, enantiopure pincer ligand 2,6-bis{[(S)-2-hydroxymethyl-1-pyrrolidinyl]methyl}phenyl bromide (1) with bis-ortho-(S)-prolinol substituents was synthesized and isolated as a mixture of three stereoisomers [(SN,SN,SC,SC), (RN,SN,SC,SC), and (RN,RN,SC,SC)] in a 1:1:1 ratio. Upon abstraction of the bromide ion from the unresolved mixture of 2, single diastereoisomers of the cationic complexes [3]BF4 and [3]PF6, respectively, were formed with a uniqueη4-N,C,N,O coordination mode of ligand 1. X-ray crystal structure determination established the intramolecularη4-N,C,N,O coordination of 1 to palladium where the typical mer-η3-N,C,N pincer coordination is accompanied by coordination of one of the hydroxy groups of the (S)-prolinol moieties. The water molecule that was cocrystallized in the crystal structure of [3]PF6 does not coordinate to palladium, but instead is involved in a hydrogen bonding network. The catalytic potential of both cationic complexes, [3]BF4 and [3]PF6, was tested in an aldol reaction of aldehydes with methyl isocyanoacetate to yield the oxazoline products as racemic mixtures.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
TL;DR: The mercaptopyridine complexes are the first reported examples of pincer-ligated Pd and Pt thiolate species and the pyridine ligands can be quantitatively exchanged for chloride by reaction with excess NH4Cl, a potentially useful chemical switch for ligation/decomplexation of this ligand type.
Abstract: A silver-free route has been employed for the synthesis of a number of Pd and Pt complexes supported by an NCN "pincer" ligand (NCN = [2,6-(Me2NCH2)2C6H3]-) via halide abstraction. This was achieved by the use of o-, m-, and p-hydroxypyridines or o- and p-mercaptopyridines in basic ethanol solutions. The acidic OH or SH protons are removed to generate the formally anionic ligands. X-ray crystal structure determination of these complexes shows that the bonding of the substituted pyridine ligands occurs exclusively through the pyridine N for hydroxypyridines and exclusively through the thiol S in mercaptopyridines. In the hydroxypyridine case, the ortho and para isomers tautomerize to generate pyridone structures with a covalent M-N bond, whereas the m-hydroxypyridine complex, which is unable to tautomerize, is found to still be bound through the pyridine N but in a zwitterionic structure. The mercaptopyridine complexes are the first reported examples of pincer-ligated Pd and Pt thiolate species. The pyridine ligands can be quantitatively exchanged for chloride by reaction with excess NH4Cl, a potentially useful chemical switch for ligation/decomplexation of this ligand type.
TL;DR: In this paper, the naphthide radical anion was shown to undergo ring protonation by water to form 1,4-dihydronaphthalene and naphthalenes in a 1:1 ratio.
Abstract: Reduction of the new, naphthalene-based pincer complex [(C10H5(CH2PiPr2)2)Rh(η1-N2)] with potassium metal gave the corresponding σ-coordinated naphthyl radical anion complex, with a ring-centered radical and no change in the formal metal oxidation state. This paramagnetic complex can be reoxidized to the diamagnetic one with [Cp2Fe][BF4], the structural integrity being retained. Unexpectedly, treatment of a THF solution of the reduced complex with water leads to the immediate evolution of dihydrogen, with reoxidation to the starting complex. This is in striking contrast with the well-known reactivity of the naphthide radical anion, which undergoes ring protonation by water to form 1,4-dihydronaphthalene and naphthalene in a 1:1 ratio.
TL;DR: In this paper, N,N′-dibenzyl-1H-pyrrole-2,5-dicarbothioamide pincer complexes of group 10 metals with κ3SNS-type coordination were characterized.
Abstract: N-Metalation of N,N′-dibenzyl-1H-pyrrole-2,5-dicarbothioamide afforded new pincer complexes of group 10 metals with κ3SNS-type coordination. Molecular structures of the complexes were characterized...